1. Field of the Invention
The present invention relates an apparatus and method of operating a chromatography column and, more particularly, to such a chromatography column and a method for effectively packing media and/or automatically moving the top flow adapter at at least one predetermined speed less than a maximum speed and/or providing at least one programmably set bottom limit stop.
2. Description of Related Art
Chromatography is a process of separating components of a mixture of chemical substances through the percolation of fluid through a body or bed of comminuted or porous rigid material, known as media. In the process, the various component are often resolved, or separated, by their selective retardation as they are transported through the bed by a moving fluid or buffer. A solution of the substances to be separated becomes the moving phase of the system passing through the interstices in the stationary or continuous phase which are finely divided particles, possibly in the form of a gel slurry.
The substances in the moving phase are normally poured into the top of a chromatography column filled with the finely divided material, i.e., the media, that can absorb differentially the substances to be separated. The particular material used for the media varies widely with the substances to be separated. As the solution percolates down the column the components are separated from the buffer fluid which may be pumped back into the top of the column so as to again pass down through the bed as a carrier. The different substances as they travel down the column at different rates form bands of the different substances which are individually collected at the outlet.
A chromatography column typically comprises a hollow vertically disposed cylindrical housing including a liquid dispensing section, also referred to as a top flow adapter or plunger in many embodiments, at the upper end and through which the buffer and substances to be separated are dispensed to the media bed, and a liquid collecting section at the lower end for collecting the substances and buffer individually. The media or bed through which the buffer fluid and mixture to be separated and purified percolates is located between these sections. The liquid dispensing section and liquid collecting section may each include a respective distribution plate and at least one of the plates may be connected in an assembly with an axially movable plunger-like body positioned within the housing. After the column is charged with the bed media, the plunger body is often forced toward the bottom to compress or pressurize the media bed which has been poured into the column.
Prior art designs have allowed for the plunger to be moved with hydraulics manually controlled by an operator such as those shown and described in Applicant's U.S. Pat. No. 6,736,974, incorporated herein by reference. When the operator manually actuated the hydraulic controls of the prior art design, he or she would cause valves to open and shut to move the plunger up or down at a single, or maximum speed. In order to change the speed of operation of the plunger, in a prior art device, air pressure provided to a hydraulic pump could be varied manually with a regulator on the air supply. However, this process was completely operator dependent and not particularly precise. If left to normal operation with the controller, the only speed of operation was the maximum speed.
The prior art packing technique involved an operator lowering a plunger until it stopped. When lowering the plunger at its single fastest speed, when the liquid in the column was first encountered, the plunger could continue downward at this speed thereby likely continuing to pack the bed. This could lead to an undesirable pack in at least some situations.
Accordingly, a need exists to improve the operational methods by providing an improved chromatography column.